Earth based solar collector

ABSTRACT

This invention relates to the collection of sunlight for heat which is used for heating and for the conversion of heat to electricity. Where a large area of land is prepared then covered with a solar collecting film of plastic or glass. The air or water under the film being heated is then circulated around the inside of the collector over a heat exchanger. The solar collector is insulated from the ground it is constructed on and uses stone or water to retain the heat. The retained heat can extended the working time of the collector beyond the time when the sun sets. This heat exchanger carries a working fluid such as Freon that is used to perform work such as spinning an electric generator.

A BRIEF SUMMARY OF THE INVENTION

This invention relates to the collection of sunlight for heat which is used for heating and for the conversion of heat to electricity with a steam or an Organic Rankine Cycle ORC system. Where a large area of land is prepared then covered with a solar collecting film of plastic or glass. The air or water under the film will heat up and is then circulated around the collector over a heat exchanger. This heat exchanger carries a working fluid such as Freon which has been heated to perform work in the ORC system.

BACKGROUND OF THE INVENTION

The invention relates an earth based solar collector. Prior art shows how to create flat-plate or concentrating collectors however, because solar energy is a diffused energy source such devices are of limited practical value for large scale power generating systems as the complexity of such systems when scaled to a large size results in a system cost that exceeds the value of the electricity that can be generated over the useful life of the system. By using the earth itself as the back and side panels of the collector the collector cost drops from dollars per square meter to pennies per square meter. This innovation in collector design will result in lower system efficiency which is at first counterintuitive, however because of the diffused nature of sunlight it will be apparent that reducing the collector cost by an order of magnitude or more will far outweigh any reduction of efficiency. The useful temperature range of this collector will range from 150 degrees Fahrenheit to 450 degrees Fahrenheit. Prior art such as UTC Carrier patent #7,174,716 defines a low temperature ORC system that could be used with this invention.

Objects and Advantages:

Accordingly I claim the following as my objects and advantages of the invention: to provide a solar collector that uses prepared earth as a back plane and a covering plate or plates of plastic or glass. The plastic and glass can be treated to maximize their transmission of sunlight while limiting the re-radiation loss of infrared or heat energy out of the collector. The background of the collector being the earth itself will provide insulation with porous material such as vermiculite or foam insulation and the surface of the earth inside the collector will be painted or sprayed black with black material such as carbon black or a solar selective paint to maximize the ability to absorb sunlight. The angle of the earth will be modified to maximize the collectors light collecting ability, such as bulldozing the land so that the maximum amount of area faces the sun so that the maximum amount of sun light will be received. In this way very large areas of land maybe covered with this solar collector at the lowest possible cost.

In addition I claim the following as objects and advantages of the invention: to provide a solar collector system that can be built in a circular or oval manner so that the air or water inside the collector can be blown or pumped around a circular or oval path so that the hot solar heated air or water can pass through a heat exchanger so the heat can be extracted in the form of steam or a refrigerant such as Freon or other hydrocarbon may be so heated for use in a steam turbine or in the case of heated Freon or other organic fluid may be used in an ORC system for the generation of electricity.

DRAWING FIGURES

FIG. 1 shows a cross section of the solar collector.

FIG. 2 shows a 1,000 meter long collector covering a large area

DRAWING REFERENCE NUMERALS

FIG. 1

-   Element 10: insulating material -   Element 20: earth -   Element 30: solar absorbing coating -   Element 40: clear layer #1 -   Element 50: clear layer #2 -   Element 60: infrared coatings -   Element 65: insulating air-gap -   Element 70: insulating side panel -   Element 75: heated air or water -   Element 80: heat absorbing thermal mass

FIG. 2

-   Element 90: heat exchanger -   Element 100: solar collector -   Element 110: fan or pump -   Element 120: Organic Rankine Cycle—ORC system

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows an earth based solar collector where the earth 20 has been formed into a solar collector and has been formed at angles to maximize the absorption of sunlight. An insulation material 10 is used under the heat absorbing mass 80 to limit heat loss into the ground below the collector. This mass which can be water retains the collected heat above the insulation acting as a thermal buffer. The collector is covered with one or more clear membranes 40 and 50 such as glass or plastic or both. This membrane may be treated with an infrared retention coating 60 internally or externally. The sides of the collector maybe formed from the earth or insulating side panels 70 may be used.

FIG. 2 shows a large scale earth based solar collector. To extract the heated air or water 75 which is circulated with a fan or a pump 110. This heated air or water then passes over the heat exchanger 90 heating a working fluid such as Freon for use in the Orgainc Rankine Cycle system 120. 

1. A solar collector comprising: a transparent film, an air gap, heated air or water a solar selective coating, a heat retaining thermal mass, a layer of insulation, an insulating wall, a heat exchanger, a refrigerant, a fan, an Organic Rankine system.
 2. The solar collector of claim 1 wherein said collector comprises a multiplicity of transparent film layers.
 3. The solar collector of claim 1 wherein said transparent film layer has an infrared retention coating.
 4. The solar collector of claim 1 wherein said transparent film layer or layers are fabricated to retain infrared radiation.
 5. The solar collector of claim 1 wherein said transparent film layer or layers are plastic.
 6. The solar collector of claim 1 wherein said transparent film layer or layers are glass.
 7. The solar collector of claim 1 wherein said selective coating absorbs the solar spectrum.
 8. The solar collector of claim 1 wherein said thermal mass consists of stone or stone like material.
 9. The solar collector of claim 1 wherein said thermal mass is water.
 10. The solar collector of claim 1 wherein said thermal mass is placed above an insulating layer retaining the heat in the collector.
 11. The solar collector of claim 1 wherein said side wall is an insulating material retaining the collected heat in the collector.
 12. The solar collector of claim 1 wherein said heat exchanger extracts heat from the said heated air within the collector.
 13. The solar collector of claim 1 wherein said refrigerant transfers the heat energy from the collector.
 14. The solar collector of claim 1 wherein said refrigerant is a fluid like Freon or other organic fluid used in said Organic Rankine Cycle system.
 15. The solar collector of claim 1 wherein said fan is used to move the heated air around the inside of the collector over the heat exchanger.
 16. The solar collector of claim 1 wherein said pump moves the heated water around the inside of the collector over the heat exchanger. 